Qin Zhou

Functionalization of carbon nanotubes by argon plasma-assisted ultraviolet grafting

We have demonstrated the functionalization of single-wall carbon nanotubes (SWNTs) by argon (Ar) plasma-assisted ultraviolet (UV) grafting of 1-vinylimidazole (VZ). The Ar plasma treatment generates defect sites at the tube ends and sidewalls, which act as the active sites for the subsequent UV grafting of VZ monomer. Atomic force microscopy analyses indicate that the original nanotube bundles exfoliate to individual tubes after the VZ grafting. By control of the deposited energy of Ar plasma treatment (200W) and treatment time (5min), no visible chopping of the functionalized SWNT was observed. This method may be extended to other vinyl monomers and offers another diverse way of sidewall functionalization of SWNT.

Functionalized multi-walled carbon nanotubes as affinity ligands

Functionalization of carbon nanotubes is very challenging for their applications. The paper here describes a new method to functionalize multi-walled carbon nanotubes (MWCNTs) as specific affinity adsorbents. MWCNTs were acid purified and pretreated with (3-aminopropyl)-triethoxysilane (APTES) in order to introduce abundant amino groups on the surface of MWCNTs. After the conversion of amino groups to carboxyl groups by succinic acid anhydride, MWCNTs were attached to protein A or aminodextran using 1-ethyl-3,3 (dimethylamion)-propylcarbodiimide as a biofunctional crosslinker. The incorporation of aminodextran as a spacer arm noticeably increased the binding capacity of the APTES-modified MWCNTs for protein A. The application of affinity MWCNTs for purification of immunoglobulin G was then evaluated. The affinity of MWCNTs with AMD spacer exhibited a high adsorption capacity of ~361??g IgG/mg MWCNT (wet basis). About 75% of bound IgG was eluted from affinity MWCNTs (ANT-I and ANT-II) and ELISA confirmed that the biological activity of IgG was well preserved during the course of affinity separation. The functionalized MWCNTs could be potentially used in affinity chromatography.

Fabrication of thin-film organic transistor on flexible substrate via ultraviolet transfer embossing

Organic field-effect transistors with large-area coverage on flexible plastic substrates are fabricated by ultraviolet transfer embossing printing method. The source and drain electrodes are formed on the plastic substrate with gold by means of transfer embossing. The active layer is spin coated from 5wt% poly(3-hexylthiophene)-chloroform solution. Poly(4-vinylphenol) is used as the dielectric layer and a thin layer of silver paste is applied to cover the channel area as the gate electrode. The device shows good saturation behavior and gives an on/off ratio of 102 and the extracted field-effect mobility of the transistor is 0.0016cm2∕Vs.

Biochips – fundamentals and applications

Publisher Summary Biochip, a bio-microarray device, has been extensively studied and developed to enable large-scale genomic, proteomic and functional genomic analyses. A biochip comprises mainly three types: DNA microarray, protein microarray, and microfluidic chip. With the integration of microarray and microfluidic systems, a micro total analysis system, which is often called a lab-on-a-chip (LOC) system, is produced. Advances of nanotechnology have continuously reduced the size of the biochip which in turn reduced the manufacturing cost and increased the high throughput capability. Due to the benefits of low expense, high throughput and miniaturization, this technology has great potential to be a crucial and powerful tool for clinical research, diagnostics, drug development, toxicology studies, and patient selection for clinical trials. The greatest advantage of the DNA arrays is its speed and high throughput and they are useful in various genomic applications, including single nucleotide polymorphism (SNP) analysis, gene expression studies, disease classification, function prediction, pathway identification, new drug development, clinical diagnostics, and toxicology studies. Protein chips, especially functional microarrays, are used to study basic biological properties like examining protein interactions with other ligands such as proteins, peptides, lipids or other molecules. The most common use of protein microarrays is in immunoassays, and they also played a significant role in the development of safer drugs through the comprehensive profiling of drugs or lead compounds for effects. LOCs are capable of conducting various types of chemical and cellular analysis, separations and reactions. LOC is one of the fastest growing areas of microfabrication and nanotechnology development, integrating many technologies to develop applications in a wide range of disciplines including genetic analysis, disease diagnosis, culturing and manipulating cells, drug discovery, and materials chemistry.